Automatic belt-tightener.



PATNTD DEG. 1904.

H. E. CLARK.

AUTOMATIC BELT TIGH'IENER.

APPLICATION FILED BEPT. 20, 1904.

.N0 MODEL.

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Patented December 6, 196%.

PATENT HERBERT E. CLARK, CF SAN FRANCISCO, CALIFORNIA.

AUTOMATIC BELT-TIGH'f'iEN EH.

SPECIFCATION forming-part of Letters Patent No. 776,827,

dated December 6, 1904.

application filed September 20, 1904i. Serial No. 225,197. (No model.)

To fir/ZZ wir/071i, it muy concern:

Be it known that I, Hummer E. CLARK, a citizen ofthe United States, residingin the city and county of San Francisco, State of California,liave invented certain new and useful 'Improvements in Automatic Belt-Tighteners; and il do hereby declare the following to be a full, clear, and exact description of the same.

The present invention relates to certain new and useful mechanism for automatically adjusting and regulating the tension of an endless drive-belt in accordance with variation in the load changes, the object being to maintain the proper degree of tension onto the said endless drive-belt irrespective of the load placed onto the power-drum, the invention consisting in certain details of construction and novel arrangement of parts hereinafter more fully set forth and described.

In order to comprehend the invention, reference should be had to the accompanying sheet of drawings.

Figure 1 is a side view in elevation of the tightening mechanism, said View disclosing the endless drive-belt and the drive-pulley and power-pulley over which the same works. Fig. 2 is a vertical sectional end View in elevation, taken on line ai a, Fig'. 1 of the drawings, and Viewed in the direction of the arrow; and Fig. 3 is a detail view of the shaft for the power-drum, the gear thereon, and the 1i)awl-and-ratchet connection with the shaft.

1n the drawings the numeral 1 is used to indicate an ordinary drive-pulley; 2, the powerpulley, and 3 the endless drive-belt. rEhe pulleys 1 2 are mounted on shafts i 5,1-espectively, which shafts work in bearingboxes supported by the standards or frames 6 7. Preferably to the standands or frame 7 the upwardly-extending brackets 8 are connected, which brackets at their outer end carry the bearing-boxes 9 for the cross-shaft 10. To the projecting' ends of this cross-shaft the swinging arms 11 12 are fulcrumed, which arms normally extend upward at an angle to the brackets 8. These arms at their upper ends carry the bearingboxes 13, in which Work the cross-shaft 14. Cn the said crossshaft 14 is mounted the idler-roll 15, which roll rides or bears upon the upper face of the endless drive-belt 3, the tension of which belt it is designed to automatically control to prevent slippage thereof over the power-pulley 2. There is also secured on thecrossshaft 14 a cog-pinion 16, whichpinion meshes with a larger cog' -gear 17. The said coggear 17 is mounted on the cross-shaft 10, and the said cog-gear meshes with a smaller coggear 18, loosely mounted on an inwardlyprojecting' stud 19. The said cog-gear 18 in turn meshes with the coggear 2.0`v loosely mounted on the cross-shaft 5.

The cog-gear 2O has secu red to the outerface thereof a series of pawls21, which pawls eugage with the teeth of the ratchet 22, secured to and rotating with the cross-shai`t By means of the pawl-and-ratchct mechanism the cog-gear 20 is caused to rotate with and is positively driven in the same direction as that of the cross-shaft Hence the moment rotation is given the said cross-shaft 5 corresponding motion or rotation is imparted to the said oog-gear 20, which in turn transmits its motion to the larger cog-gear 17 through the medium of the intermeshingcoggear 18.

It will be understood that the idler-roll 15 is driven by the friotional contact therewith of the endless d rive-belt 3, the upper surface of which.I as stated, bears upon or against the peripheral surface of the said roll .15.

The arms 1 1 12 have a constant downward tension or strain exerted thereon by means of the springs 23, which springs are attached to the cross-shaft 10, the outer or free end 'thereof bearing` against the pins 23', projecting from the said fulcrumed arms 11 12. ',lhe purpose of this spring tension is to enable the arms 11 12, carrying the idler-roll 15, to offset the tendency of the idler-roll 15 toward vibration and at the same time to hold the said idler-roll firmly down to and against the surface of the endless drive-belt 3.

The operation of the device is as follows: Presuming that motion is being imparted to the endless drive-belt 3 and the same to be slipping over the power-drum 2, the frictional Contact of the said endless drive-belt with the idler-roll 15 imparts rotation thereto. As this is rotated therewith, engaging with the larger l il idler-roll is rotated the cog-pinion 16, which gear 17, gradually works over the said gear, causing the arms 11 12 to move downwart and forcing the idler-roll 15 to gradually tighten down onto the endless drive-belt 3 in order to tighten the same until the tension thereof onto the drum 2 is sufficient to impart rotation thereto. rlhe moment rotation is imparted to the drum 2 a corresponding motion is transmitted to the described train of gear mechanism, thus transmitting a speed to the train of gears proportionate to the speed at which the powerdrum 2 is driven. The moment rotation is imparted to the train of gears the downward movement of the idlerroll 15A ceases, and said roll and the train of gears will be driven proportionately at the same rate of speed. It is thus obvious that the tension of the endless drivenbelt is automatically regulated in proportion to the load changes of the power-drum 2, for any change or variation of said load will cause a proportionate change in the tension of the endless driven belt onto the power-drum, which necessitates automatic regulation of said tension, which is accomplished through the rnedium of the described mechanism. So long as the tension of the endless driven belt 3 onto the surface of the power-drum 2 is sufficient to cause rotation of the said power-drum at the requisite speed for the working loadthe position of the idler-roll 15 will remain normal and the train of gears will be rotated at a speed proportionate to that of the powerdrum 2. However, the moment there is a change or variation in the working load placed onto the power-drum 2 the idler-roll 15 will automatically adjust the tension of the endless driven belt proportionately thereto.

Having thus described the invention, what is claimed as new, and desired to be protected.

by Letters Patent, isg

1. A belt-tightener, the same comprising an idler-roll which is frictionally engaged by the endless drive-belt, and connections between the said roll and the shaft of a power-drum,

said connectidns being positively driven by the rotation ofthe power-drum shaft and serving to hold the idler-roll in its adjusted position as long as the tension of the belt is proportionate to the working load.

2. The combination with an endless drivebelt, of a power-drum over which the same works, an idler-roll mounted above the endless drive-belt and frictionally driven thereby, swinging means for supporting the idler-roll, a train of gear mechanism driven from the shaft of the power-drum when rotation is imparted thereto, and connection between said mechanism and the idler-roll, which permits of the said roll being lowered or raised to regulate the tension of the endless drive-belt proportionate to the working load of the powerdrum.

8. In a belt-tightener, the combination with the idler-roll which bears onto the endless drive-belt, and connected mechanism for automaticall y raising and lowering the idler-roll to adjust the tension of the endless drive-belt proportionately to the working load of the means driven thereby.

L1. The combination with the power-drum, of the endless drive-belt, an idler-roll which bears onto the drive-belt, swinging support for the idler-roll, a cog-gear loosely mounted on the shaft for the power-drum, pawl-andratchet connection between the saidv gear and the shaft so as to positively drive the gear with the shaft, an intermediate gear driven by the gear mounted on said shaft, a larger gear with which the intermediate gear meshes, and a cog-pinion operated by the rotation of the idler-roll, said pinion meshing with the larger cog-gear and working' thereover to raise and lower the idler-roll to adjust the tension of the endless drive-belt proportionate to the working load of the power-drum.

1n witness whereof I have hereunto set my hand.

HERBERT E. CLARK.

Titnessesz N. A. ACKER,

D. B. RICHARDS. 

